In this contribution, we report a facile preparation method of nickel cobalt oxide-reduced graphite oxide (NiCo 2 O 4 -rGO) composite material. A fast Faradic process has been realized by sodium dodecyl sulfate (SDS)-induced ultrasmall NiCo 2 O 4 nanocrystals on rGO. As a result, this composite material gives a high specific capacitance of 1222 F g À1 at 0.5 A g À1 and 768 F g À1 at 40 A g À1 , showing an outstanding rate capability. An asymmetric supercapacitor device with high energy and power densities has been successfully assembled based on NiCo 2 O 4 -rGO composite material and activated carbon. The optimized device shows a high energy density of 23.32 Wh kg À1 at a power density of 324.9 W kg À1 . In addition, this asymmetric device shows good stability towards multistage current charge-discharge cycles.